Silylmethylene methacrylate contact lens and polymer

ABSTRACT

Silylmethylene metharcylate polymers and optical contact lenses fabricated therefrom are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of my copending application Ser. No.742,122, filed June 5, 1985, now abandoned, which, in turn, is acontinuation-in-part of then copending application Ser. No. 641,594,filed Aug. 17, 1984, now abandoned.

FIELD OF THE INVENTION

This invention relates to optical contact lenses and materials thereforeand, in particular, to alkylsilane polymers and alkylsilane polymercontact lenses.

BACKGROUND OF THE INVENTION

Many polymeric materials have been evaluated for potential utility ascontact lens material, but a very limited number of materials have beenfound to form contact lenses which are satisfactory. Advances in contactlens materials and techniques have come in small steps, which have beenexcruciatingly slow and difficult. Polymers and methods which appearedattractive have fallen by the wayside. The problems are myriad, andpredictability is low. It is difficult and frequently impossible topredict optical quality, strength and flexibility, resistance to proteinbuildup, machining and fabrication characteristics, dimensionalstability, oxygen permeability, and general biological compatibility. Itis impossible to predict, or even to speculate as to possible optical,oxygen permeability, and biological characteristics of structural andindustrial silanes such as disclosed by Campbell, U.S. Pat. No.2,958,681 for example.

Reference is made to the literature, in texts, treatises and technicalliterature which describe silicon compounds, commonly referred to assilanes, particularly alkylsilanes. While the present invention departsfrom this chemistry in important and substantial ways, this body ofchemistry is fundamental to the present invention.

Silane chemistry is quite well known and reported in the literature. Anexcellent treatment of the chemistry of silanes is given by Sommers, L.H.; Mitch, F. A.; and Goldberg, G. M., "Synthesis and properties ofCompounds with a Framework of Alternatesilicon and Carbon Atoms,"J.A.C.S., 71, 2746, (1949). Surveys of this body of chemistry are foundin KIRK-OTHMER, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, 3rd Ed. at Vol. 20,pp. 887-991. The chemistry of organosilicon compounds is described inORGANOSILICON COMPOUNDS, Bazant, Chvalovsky and Rathovsky, AcademicPress, Inc., New York, 1965.

Silanes have been utilized in preparative organic chemistry and for anumber of specialty applications, including waterproofing compounds formortar and fabrics and the like, as accelerators in some polymeroperations, and as intermediates in the preparation of organosiloxanes.

Upchurch, U.S. Pat. Nos. 4,528,301 and 4,616,045 mention, inter alia,contact lenses of copolymers in which one monomer is selected from "asubstituted polysiloxane such as dimethyl polysiloxane or a substitutedsilane" and refers to dimethyl, ethyl, phenyl, methoxy, vinyl,fluoropropyl, cyano, dimethylphenyl substituted silanes and mixtures ofthe same; however, this reference to silane monomers as constituents incontact lens polymers is apparently a shot in the dark. No examples ofsilane-containing contact lenses are given and it is not apparent fromUpchurch, supra, that it would even be possible to prepare asilane-containing contact lens.

Takahashi, et al, U.S. Pat. No. 4,594,401 discloses contact lenses inwhich a substantial or major monomeric component in the polymer of whichthe lens is formed is trimethylsilylstyrene ##STR1## While Takahashi etal disclose an increase in oxygen permeability in lenses in whichtrimethylsilylstyrene is a major constituent, and suggest that a limitedclass of trimethylsilyl compounds, e.g. trimethylsilylmethylmethacrylate, trimethylsilylmethyl acrylate, trimethylsilylpropylmethacrylate, and trimethylsilylpropyl acrylate may be substituted,there is no disclosure or suggestion of the use of more complexdisylylemethylenes as lens polymer constituents. In view of the highlevel of uncertainty and lack of predictability vis-a-vis whether or nota given polymer can be made to form lenses, whether it will betransparent, have a suitable refractive index or hardness, etc., onecannot predict from the prior art whether or not silylmethylenemethacrylate compounds may be incorporated into polymers which will formsuitable contact lenses.

SUMMARY OF THE INVENTION

The present invention relates to a novel class of contact lensescomprising polymers resulting from the polymerization orcopolymerization of silylmethylenes having the general structure:##STR2## i.e. two or more silicon atoms chained together by one or morecarbon atoms, n is a positive integer from 1 to 5, preferably 1 to 3 andwherein R₁ through R₆ are selected from the group consisting of methyl,phenyl, ##STR3## alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl, atleast one of R¹ through R⁶ comprising a polymerizable vinyl groupselected from vinyl, allyl, acrylyl, acrylyl, methacrylyl, ethacrylyl,or styryl groups. (See Sommer et al, supra, for early disclosure ofsimpler examples of disilylmethylenes generally.)

Exemplary compounds include: ##STR4## wherein n is a positive integerfrom 1 to 5, preferably 1 to 3; ##STR5## wherein n is a positive integerfrom 1 to 5, preferably 1 to 3; ##STR6## wherein n is a positive integerfrom 1 to 5, preferably 1 to 3 and R₁, R₂, R₃ and R₄ are selected fromthe group consisting of methyl, phenyl, ##STR7## alkyloxy, phenylmethyl,and N-alkyl-pyrrolidinonyl; ##STR8## wherein n is a positive integerfrom 1 to 5, preferably 1 to 3; ##STR9## wherein n is a positive integerfrom 1 to 5, preferably 1 to 3 and R₁ and R₂ are selected from the groupconsisting of methyl, phenyl, ##STR10## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl; ##STR11## wherein n is a positive integer from 1to 5, preferably 1 to 3 and R₁ and R₂ are selected from the groupconsisting of methyl, phenyl, ##STR12## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl; ##STR13## wherein n is a positive integer from 1to 5, preferably 1 to 3 and R₁ through R₄, inclusive, are selected fromthe group consisting of methyl, phenyl, ##STR14## alkyloxy,phenylmethyl, and N-alkyl-pyrrolidinonyl; ##STR15## wherein n is apositive integer from 1 to 5, preferably 1 to 3 and R₁ and R₂ areselected from the group consisting of methyl, phenyl, ##STR16##alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl. Silanes with twopolymerizable groups and polymers thereof and lenses of such polymersare also contemplated within the scope of the invention. Exemplary ofsuch monomers are: ##STR17## wherein n is a positive integer from 2 to5, preferably 2 or 3 and R₁ and R₂ are selected from the groupconsisting of methyl, phenyl, ##STR18## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl; ##STR19## wherein n is a positive integer from 1to 5, preferably 1 to 3 and R₁ through R₄, inclusive, are selected fromthe group consisting of methyl, phenyl, ##STR20## alkyloxy,phenylmethyl, and N-alkyl-pyrrolidinonyl;

A monomer which is predominantly silane, even though it includes theSi--O--Si linkage, is: ##STR21## wherein n is a positive integer from 1to 5, preferably 1 to 3, and R₅ to R₈, inclusive, are selected from thegroup consisting of ##STR22##

Other monomers which include two polymerizable groups include: ##STR23##wherein n is a positive integer from 2 to 5, preferably 2 to 3 and R₁and R₂ are selected from the group consisting of methyl, phenyl,##STR24## alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl; ##STR25##wherein n is a positive integer from 2 to 5, preferably 1 to 3 and R₁and R₂ are selected from the group consisting of methyl, phenyl,##STR26## alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl; ##STR27##wherein n is a positive integer from 1 to 5, preferably 1 to 3;##STR28## wherein R₉ and R₁₀ are selected from the group consisting ofmethyl, phenyl, ##STR29## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl;

In general, vinyl, allyl, acrylallyl, acrylic, methacrylic or ethacrylicderivatives of the compounds referred to which include one or morepolymerizable groups such as vinyl, allyl, acrylic, methacrylic orethacrylic may be considered equivalent to the specific, exemplarymonomers, and polymers and copolymers of the same may be used as contactlens materials and lenses.

The silylmethylene methacrylate polymer lenses of this invention havebeen discovered to have extremely beneficial, and most unexpected andunpredictable properties as contact lenses. For example, the mostcomparable lenses, of siloxyl based polymers, have an oxygenpermeability, Dk value (see, e.g. Fatt, I. and St. Helen, R., OxygenTension Under an Oxygen-Permeable Contact Lens, American Journal ofOptometry, July 1971, pp. 545-555, for a discussion of Dk values) in the20's, the highest being about 30 to 32. The silylmethylene methacrylatepolymer lenses of this invention have a calculated Dk value of as highas 40 or more! The extremely high Dk value, as shown by wearer comfort,has been demonstrated for the contact lenses of this invention. Inaddition, these silylmethylene methacrylate polymer lenses have an evengreater resistance to protein contamination than the silicone andmonosilane polymer lenses. These silylmethylene methacrylate polymerlenses are also harder and, very surprisingly, can be made wettable byinclusion of appropriate hydrophilic substituents much more easily thancomparable silicone polymer contact lenses! These very surprisingadvantages, coupled with good optical quality, could not have beenpredicted or even guessed at in advance. These lens polymers can beformulated with a relatively high phenyl substituent content, givinglenses having a high index of refraction which can be made thinner andlighter than conventional contact lenses, and more easily fabricatedinto bifocal lenses than is possible with conventional and known lenspolymers. Surface characteristics can be modified by inclusion ofspecific moieties in the polymer; for example, methoxy alkyl, ethoxyalkyl, or n-alkylpyrrolidinone may be included to improve wettability.Monomers having two polymerizable groups may be used, thus resulting ina fully cross-linked lens polymer. It is even possible to prepare highlyhydrated lenses from the polymers of this invention!

DESCRIPTION OF THE PREFERRED EMBODIMENT

No new silane chemistry, per se, is involved in the present invention;rather, it has been discovered that silylmethylene methacrylate polymercontact lenses have most unexpected and unpredicted advantages overother lenses and, more particularly, over the most comparable lenses,those formed of silicone polymers.

The silylmethylene methacrylates used in forming the polymers from whichthe lenses of the present invention are manufactured are mostconveniently prepared by the action of a polymerizable vinyl groupcontaining moiety, e.g. methacrylic acid, on a chloroalkyl or bromoalkylsubstituted silane, such as chloromethyl trimethylsilane ordi-chloromethyl dimethylsilane, in the presence of a base such aspyridine or triethyl amine. The higher homologues of the series areconveniently prepared by the action of the Grignard Reagent of a silane,such as trimethylsilylmethyl magnesium chloride on a chlorosilyl-alkylmethacrylate, e.g. trichlorosilyl propyl methacrylate, to givetris(trimethylsilylmethyl) silyl-propyl methacrylate.

LENS MANUFACTURE

The following general technique was followed in the preparation of lensblanks and lenses:

Monomers in the specified ratio and initiator were thoroughly mixed anddried over magnesium sulfate and filtered. The dried, filtered monomermixture was placed in molds under nitrogen atmosphere and cured byslowly raising the temperature to about 100° C. for about 2 hoursfollowed by a reduction to a post-cure temperature of about 80° C. for apast cure of about 15 hours. The resulting lens blank was examined andis then machined to form contact lenses according to conventionalprocedures for the manufacture of contact lenses.

The following examples of lenses formed by the technique describedexemplify the invention.

EXAMPLE 1

    ______________________________________                                        Phenyltetramethyldisilylmethylene-                                                                       50%*                                               methylmethacrylate                                                            Methyl methacrylate      38.5%                                                Methacrylic acid           6%                                                 Ethylene glycol dimethacrylate                                                                           5%                                                 N--vinylpyrrolidinone      3%                                                 Initiator**              (Trace)                                              Initial Cure Temperature  100° C.                                      Initial Cure Time         2 hours.                                            Post Cure Temperature    82-83° C.                                     Post Cure Time           17 hours.                                            Lens Qualities:                                                               Clarity                  Excellent                                            Hardness                 Good                                                 Machinability            Good                                                 Wettability              Good                                                 Dimensional Stability    Excellent                                            ______________________________________                                    

This lens material has an exceptionally high refractive index, making itideally suited to the manufacture of bifocal and thin lenses.

These lens materials had excellent optical properties and some hadoutstanding refractive index characteristics. All were ideal for themanufacture of high quality exceptionally comfortable lenses. Some hadmoderate to high hydration capacity, in addition to being excellent,clear, comfortable lens characteristics.

One of the important discoveries of this invention is that these lensmaterials are far more comfortable for the wearer than the most nearlycomparable lenses formed of siloxanyl polymers, the silicone polymers ofthe prior art and of my earlier filed copending patent applications.Wearer comfort is somewhat subjective but reflects real differences. Twoobjective observations are believed to explain the unexpectedly highcomfort factor of the lenses of this invention. First, oxygenpermeability is very high, thus contributing to healthier eye tissue andgreater comfort. Second, these lens materials are exceptionallyresistant to the buildup of proteins on the lens surfaces.

A third, highly unexpected, factor believed to contribute to wearercomfort is the wettability of the lens materials of this invention.Silanes have typically been used in waterproofing applications and onewould predict a highly hydrophobic lens material. Quite surprisingly,however, the lenses of this invention are quite hydrophilic and, indeed,in some formulations, hydrate to a moderate to high level.

Another surprising characteristic of lens materials of the presentinvention is that it is possible to form excellent lens materials withexcellent optical, refractive, mechanical and comfort properties withoutthe presence of methyl methacrylate, or with only very minor amounts ofmethyl methacrylate.

It will be readily understood by those skilled in the art that theforegoing lens material formulations are only exemplary of a vast numberof lens materials and lenses which can be manufactured within the scopeof this invention. Many analogous and homologous monomers of the silanefamily may be substituted for those shown in the examples. Initiatorsmay be selected from among the many which are suitable for initiatingthe polymerization of vinyl-group-containing monomers.

In general, the silylmethylene methacrylates of this invention comprisegreater than 5% and preferably greater than 20% of the polymeric lensesand lens materials and may comprise up to about 95%, preferably up toabout 90%, of such materials and lenses. In the preferred embodiment,the lens material is formed from the polymerization ofpolysilylmethyenes with a crosslinking monomer and a monomer, such asn-vinylpyrrolidinone or hydroxyethyl methacrylate, or both, whichcontributes to the wettability or hydration of the lens, or to bothwettability and hydration of lenses. This hydrophilic constituent maycomprise, preferably, at least 2 to 3% and may comprise up to about 75%or more of the polymeric lens material.

Exemplary percentages of selected formulations are shown in thefollowing table:

EXAMPLE 2

    ______________________________________                                        Silylmethylene methacrylates                                                                        5 to 95 weight %                                        Methyl methacrylate   1 to 50 weight %                                        N--vinyl pyrrolidinone                                                                              1 to 50 weight %                                        Methacrylic acid      1 to 10 weight %                                        Ethylene glycol dimethacrylate                                                                      1 to 10 weight %                                        ______________________________________                                    

EXAMPLE 3

    ______________________________________                                        Pentamethyldisilylmethylene-                                                                       (35 wt. %)                                                                              3.5 g.                                         methyl methacrylate                                                           2,2,2-Trifluoroethyl methacrylate                                                                  (54 wt. %)                                                                              5.4 g.                                         Diethyleneglycol dimethacrylate                                                                    (5 wt. %) 0.5 g.                                         Methacrylic acid     (6 wt. %) 0.6 g.                                         Initiator                      Trace                                          ______________________________________                                    

EXAMPLE 4

    ______________________________________                                        Phenyltetramethyldisylilmethylene-                                                                  (40 w/o) 4.0 g.                                         methyl methacrylate                                                           2,2,2-Trifluoroethyl methacrylate                                                                   (50 w/o) 5.0 g.                                         Diethyleneglycol dimethacrylate                                                                     (4 w/o)  0.4 g.                                         Methacrylic acid      (6 w/o)  0.6 g.                                         Initiator                      Trace                                          ______________________________________                                    

As will be apparent from the above, the polymers and lenses of thisinvention comprise from five to ninety weight percent silylmethylenemethacrylate, and preferably from about 15 wt.% and 75 wt.%disilylmethylene or one of the analogs thereof.

Polymer buttons formed pursuant to the description given using theexample formulations resulted in clear, hard lenses when machined tolens configuration. The lenses were hard and easily formed, comfortableto wear and, especially the fluorine containing lenses, had a mostunexpectedly high--five to six times better than comparable silicone andnon-silane acrylic lenses. These lens materials have an exceptionallyhigh refractive index, making it ideally suited to the manufacture ofbifocal and thin lenses.

Typically, in the preferred embodiments, a hydrophilic monomer wouldalso comprise the polymerization mix.

It has also been found advantageous to include methacrylic acid and/ormethyl methacrylate as a monomer in the formation of the polymerizedlens material; however, one of the surprising discoveries of thisinvention is that high quality lenses can be formed without either ofthese constituents.

Polymeric materials resulting from the polymerization orcopolymerization of di-, tri- or other silylmethylene methacrylates, ofwhich several examples are given, and lenses formed therefrom areconsidered to be within the scope of this invention. Substituents on thebasic polysilylmethyene structure may include hydrogen or alkyl, aryl,aralkyl, or silyl moieties, which may include vinyl, allyl, acrylyl,acrylic, methacrylic, ethacrylic, or pyrrolidinonyl substituents and mayalso contain up to about 35 weight percent siloxyl. The monomer includesat least vinyl polymerizable group containing moiety or equivalent, i.e.a polymerizable group which can be reacted polymerically withoutdestruction of the polysilyl structure. The term "vinyl polymerizablegroup" is used here in a particular sense to mean a polymerizable groupcontaining the carbon-carbon double bond which is polymerized in theformation of polyvinyl polymers, i.e. the following structures:

    --C═C--

and

    --C--C═C--;

exemplary of which vinyl polymerizable groups are: vinyl, allyl,acrylyl, acrylyl, methacrylyl, or styryl.

In general, vinyl, allyl, acrylallyl, acrylic, methacrylic or ethacrylicderivatives of the compounds referred to which include one or morepolymerizable groups such as vinyl, allyl, acrylic, methacrylic orethacrylic may be considered specific, exemplary monomers, and polymersan copolymers of the same may be used as contact lens materials andlenses.

INDUSTRIAL APPLICATION

This invention is useful in the optical industry and, particularly, inthe manufacture of optical contact lenses for the correction of certainhuman vision defects.

What is claimed is:
 1. A contact lens comprising polymer resulting fromthe polymerization or copolymerization of silylmethylenes, having thegeneral structure ##STR30## i.e. two or more silicon atoms chainedtogether by one or more carbon atoms, n is a positive integer from 1 to5, preferably 1 to 3 and wherein R₁ through R₆ are selected from thegroup consisting of methyl, phenyl, ##STR31## alkyloxy, phenylmethyl,and N-alkyl-pyrrolidinonyl, at least one of R¹ through R⁶ comprising apolymerizable vinyl group selected from vinyl, allyl, acrylyl,methacrylyl, ethacrylyl, or styryl groups.
 2. A contact lens comprisingpolymer resulting from the polymerization of copolymerization ofsilylmethylenes, having the general structure ##STR32## wherein n is apositive integer from 1 to
 5. 3. A contact lens comprising polymerresulting from the polymerization or copolymerization ofsilylmethylenes, having the general structure ##STR33##
 4. A contactlens comprising polymer resulting from the polymerization orcopolymerization of silylmethylenes, having the general structure##STR34## wherein n is a positive integer from 1 to
 5. 5. A contact lenscomprising polymer resulting from the polymerization or copolymerizationof silylmethylenes, having the general structure ##STR35## wherein n isa positive integer from 1 to 5 and R₁, R₂, R₃ and R₄ are selected fromthe group consisting of methyl, phenyl, ##STR36## alkyloxy,phenylmethyl, and N-alkyl-pyrrolidinonyl.
 6. A contact lens comprisingpolymer resulting from the polymerization or copolymerization ofsilylmethylenes, having the general structure ##STR37##
 7. A contactlens comprising polymer resulting from the polymerization orcopolymerization of silylmethylenes, having the general structure##STR38## wherein n is a positive integer from 1 to
 5. 8. A contact lenscomprising polymer resulting from the polymerization or copolymerizationof silylmethylenes, having the general structure ##STR39## wherein n isa positive integer from 2 to 5 and R₁ and R₂ are selected from the groupconsisting of methyl, phenyl, ##STR40## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl.
 9. A contact lens comprising polymer resultingfrom the polymerization or copolymerization of silylmethylenes, havingthe general structure ##STR41## wherein n is a positive integer from 1to 5 and R₁ through R₄, inclusive, are selected from the groupconsisting of methyl, phenyl, ##STR42## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl.
 10. A contact lens comprising polymer resultingfrom the polymerization or copolymerization of silylmethylenes, havingthe general structure ##STR43## wherein n is a positive integer from 1to 5 and R₅ to R₈, inclusive, are selected from the group consisting of##STR44##
 11. A contact lens comprising polymer resulting from thepolymerization or copolymerization of silylmethylenes, having thegeneral structure ##STR45## wherein n is a positive integer from 2 to 5and R₁ and R₂ are selected from the group consisting of methyl, phenyl,##STR46## alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl.
 12. Acontact lens comprising polymer resulting from the polymerization orcopolymerization of silylmethylenes, having the general structure##STR47## wherein n is a positive integer from 2 to 5 and R₁ and R₂ areselected from the group consisting of methyl, phenyl, ##STR48##alkyloxy, phenylmethyl, and N-alkyl-pyrrolidinonyl.
 13. A contact lenscomprising polymer resulting from the polymerization or copolymerizationof silylmethylenes, having the general structure ##STR49##
 14. A contactlens comprising polymer resulting from the polymerization orcopolymerization of silylmethylenes, having the general structure##STR50## wherein R₉ and R₁₀ are selected from the group consisting ofmethyl, phenyl, ##STR51## alkyloxy, phenylmethyl, andN-alkyl-pyrrolidinonyl.
 15. A contact lens comprising polymer resultingfrom the polymerization or copolymerization of silylmethylenemethacrylate with a cross-linker and initiator, the silylmethylenemethacrylate comprising from about 15 to 75 wt.% of thepre-polymerization material.